Farmed salmon could be contaminated with synthetic flame retardants called polybrominated diphenyl ethers (PBDEs) if their feed is sourced from regions with little or no environmental regulations, suggests a new study, but is it a reason to avoid farmed salmon altogether?

A University of Pittsburgh study led by Dr Carla Ng, assistant professor of civil and environmental engineering at the Swanson School of Engineering, tracked the presence of PBDEs in farmed salmon.

Despite having been banned in the United States and much of Europe in 2004 because of environmental and public health concerns, PBDEs continue to be released into the environment from products manufactured before the ban of PBDEs, the study says.

“They enter the air and water and can accumulate in prey fish which are then used in the manufacture of feed ingredients,” Ng explains to Aquaculture North America (ANA).

If the exact location of the catch used as feed ingredients is unknown and/or the materials have not been tested for the presence of the pollutants, it can be difficult to tell ahead of time which animal-derived feed ingredients contain PBDEs, Ng acknowledges. But the study noted that PBDEs are particularly dense in areas such as China, Thailand, and Vietnam, countries that process a lot of electronic waste and lack rigorous regulation of their recycling industries.

Dr Neil Auchterlonie, Technical Director at IFFO, the marine ingredients organization, recognized the presence of these chemicals in “extremely small (amounts) and in generally declining concentrations.”

In deciding whether this means we should stop eating farmed salmon, Auchterlonie tells ANA: “One of the facets of the continual development of analytical technology is the identification of some of these compounds in ever-smaller concentrations. Those results are often so small that they are confusing when it comes to the interpretation of risk. That risk is important to bear in mind when taken into account with the noted benefits of consuming seafood.”

He adds that it is also important to recognize that these materials are found throughout the environment, not just in seafood. In fact, synthetic flame-retardants are everywhere. “As well as being present in the aquatic environment, PBDEs are present in the atmosphere, and in dust, which can also be sources of exposure,” he says.

Still, the risk to human health appears to be minute. A report from the Norwegian Scientific Committee for Food Safety, which covered an extensive overview of contaminants including PBDEs, concluded that the risk of adverse health effects due to PBDEs is low.

Animal nutrition specialists and fish feed manufacturers contacted for comment did not respond by our deadline.